Sequential changes in neuronal activity in single neocortical neurons after spreading depression

Cortical spreading depression (CSD) has an important role in migraine with aura. Prolonged neuronal depression is followed by a late excitatory synaptic plasticity after CSD.

Intra- and extracellular recordings were performed to investigate the effect of CSD on intracellular properties of mouse neocortical tissues in the late excitatory period.

During CSD, changes in the membrane potentials usually began with a relatively short hyperpolarization followed by an abrupt depolarization. These changes occurred roughly at the same time point after CSD as the beginning of the negative extracellular deflection. Forty-five minutes after CSD, neurons showed significantly smaller amplitude of afterhyperpolarization and a reduced input resistance. Depolarization and hyperpolarization of the cells by constant intracellular current injections in this period significantly changed the frequency of the action potentials.

These data indicate higher excitability of the neocortical neurons after CSD, which can be assumed to contribute to hyperexcitability of neocortical tissues in patients suffering from migraine.